Ars looks at the networking problems and solutions involved in getting TV to …

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Profound as it may be, the Internet revolution still pales in comparison to that earlier revolution that first brought screens in millions of homes: the TV revolution. Americans still spend more of their non-sleep, non-work time on watching TV than on any other activity. And now the immovable object (the couch potato) and the irresistible force (the business-model destroying Internet) are colliding.

For decades, the limitations of technology only allowed viewers to watch TV programs as they were broadcast. Although limiting, this way of watching TV has the benefit of simplicity: the viewer only has to turn on the set and select a channel. They then get to see what was deemed broadcast-worthy at that particular time. This is the exact opposite of the Web, where users type a search query or click a link and get their content whenever they want. Unsurprisingly, TV over the Internet, a combination that adds Web-like instant gratification to the TV experience, has seen an enormous growth in popularity since broadband became fast enough to deliver decent quality video. So is the Internet going to wreck TV, or is TV going to wreck the Internet? Arguments can certainly be made either way.

The process of distributing TV over a data network such as the Internet, a process often called IPTV, is a little more complex than just sending files back and forth. Unless, that is, a TV broadcast is recorded and turned into a file. The latter, file-based model is one that Apple has embraced with its iTunes Store, where shows are simply downloaded like any other file. This has the advantage that shows can be watched later, even when there is no longer a network connection available, but the download model doesn't exactly lend itself to live broadcasts—or instant gratification, for that matter.

Streaming

Most of the new IPTV services, like Netflix and Hulu, and all types of live broadcasts use a streaming model. Here, the program is set out in real time. The computer—or, usually by way of a set-top-box, the TV—decodes the incoming stream of audio and video and then displays it pretty much immediately. This has the advantage that the video starts within seconds. However, it also means that the network must be fast enough to carry the audio/video at the bitrate that it was encoded with. The bitrate can vary a lot depending on the type of program—talking heads compress a lot better than car crashes—but for standard definition (SD) video, think two megabits per second (Mbps).

To get a sense just how significant this 2Mbps number is, it's worth placing it in the context of the history of the Internet, as it has moved from transmitting text to images to audio and video. A page of text that takes a minute to read is a few kilobytes in size. Images are tens to a few hundred kilobytes. High quality audio starts at about 128 kilobits per second (kbps), or about a megabyte per minute. SD TV can be shoehorned in some two megabits per second (Mbps), or about 15 megabytes per minute. HDTV starts around 5Mbps, 40 megabytes per minute. So someone watching HDTV over the Internet uses about the same bandwidth as half a million early-1990s text-only Web surfers. Even today, watching video uses at least ten times as much bandwidth as non-video use of the network.

In addition to raw capacity, streaming video also places other demands on the network. Most applications communicate through TCP, a layer in the network stack that takes care of retransmitting lost data and delivering data to the receiving application in the right order. This is despite the fact that the IP packets that do TCP's bidding may arrive out of order. And when the network gets congested, TCP's congestion control algorithms slow down the transmission rate at the sender, so the network remains usable.

However, for real-time audio and video, TCP isn't such a good match. If a fraction of a second of audio or part of a video frame gets lost, it's much better to just skip over the lost data and continue with what follows, rather than wait for a retransmission to arrive. So streaming audio and video tended to run on top of UDP rather than TCP. UDP is the thinnest possible layer on top of IP and doesn't care about lost packets and such. But UDP also means that TCP's congestion control is out the door, so a video stream may continue at full speed even though the network is overloaded and many packets—also from other users—get lost. However, more advanced streaming solutions are able to switch to lower quality video when network conditions worsen. And Apple has developed a way to stream video using standard HTTP on top of TCP, by splitting the stream into small files that are downloaded individually. Should a file fail to download because of network problems, it can be skipped, continuing playback with the next file.

Where are the servers? Follow the money

Like any Internet application, streaming of TV content can happen from across town or across the world. However, as the number of users increases, the costs of sending such large amounts of data over large distances become significant. For this reason, content delivery networks (CDNs), of which Akamai is probably the most well-known, try to place servers as close to the end-users as possible, either close to important interconnect locations where lots of Internet traffic comes together, or actually inside the networks of large ISPs.

Interestingly, it appears that CDNs are actually paying large ISPs for this privilege. This makes the IPTV business a lot like the cable TV business. On the Internet, the assumption is that both ends (the consumer and the provider of over-the-Internet services) pay their own ISPs for the traffic costs, and the ISPs just transport the bits and aren't involved otherwise. In the cable TV world, this is very different. An ISP provides access to the entire Internet; a cable TV provider doesn't provide access to all possible TV channels. Often, the cable companies pay for access to content.

Walled gardens

For services like Netflix or Hulu, where everyone is watching their own movie or their own show, streaming makes a lot of sense. Not so much with live broadcasts.

So far, we've only been looking at IPTV over the public Internet. However, many ISPs around the world already provide cable-like service on top of ADSL or Fiber-To-The-Home (FTTH). With such complete solutions, the ISPs can control the whole service, from streaming servers to the set-top box that decodes the IPTV data and delivers it to a TV. This "walled garden" type of IPTV typically provides a better and more TV-like experience—changing channels is faster, image quality is better, and the service is more reliable.

Such an IPTV + Internet access service is a lot like what cable networks provide, but there is a crucial difference: with cable, the bandwidth of the analog cable signal is split into channels, which can be used for analog or digital TV broadcasts or for data. TV and data don't get in each other's way. With IPTV on the other hand, TV and Internet data are communication vessels: what is used by one is unavailable to the other. And to ensure a good experience, IPTV packets are given higher priority than other packets. When bandwidth is plentiful, this isn't an issue, but when a network fills up to the point that Internet packets regularly have to take a backseat to IPTV packets, this could easily become a network neutrality headache.

Multicast to the rescue

Speaking of networks that fill up: for services like Netflix or Hulu, where everyone is watching their own movie or their own show, streaming makes a lot of sense. Not so much with live broadcasts. If 30 million people were to tune into Dancing with the Stars using streaming, that means 30 million copies of each IPTV packet must flow down the tubes. That's not very efficient, especially given that routers and switches have the capability to take one packet and deliver a copy to anyone who's interested. This ability to make multiple copies of a packet is called multicast, and it occupies territory between broadcasts, which go to everyone, and regular communications (called unicast), which go to only one recipient. Multicast packets are addressed to a special group address. Only systems listening for the right group address get a copy of the packet.

Multicast is already used in some private IPTV networks, but it has never gained traction on the public Internet. Partially, this is a chicken/egg situation, where there is no demand because there is no supply and vice versa. But multicast is also hard to make work as the network gets larger and the number of multicast groups increases. However, multicast is very well suited to broadcast type network infrastructures, such as cable networks and satellite transmission. Launching multiple satellites that just send thousands of copies of the same packets to thousands of individual users would be a waste of perfectly good rockets.

Peer-to-peer and downloading

Converging to a single IP network that can carry the Web, other data services, telephony, and TV seems like a no-brainer.

Multicast works well for a relatively limited number of streams that are each watched by a reasonably sized group of people—but having very many multicast groups takes up too much memory in routers and switches. For less popular content, there's another delivery method that requires no or few streaming servers: peer-to-peer streaming. This was the technology used by the Joost service in 2007 and 2008. With peer-to-peer streaming, all the systems interested in a given stream get blocks of audio/video data from upstream peers, and then send those on to downstream peers. This approach has two downsides: the bandwidth of the stream has to be limited to fit within the upload capacity of most peers, and changing channels is a very slow process because a whole new set of peers must be contacted.

For less time-critical content, downloading can work very well. Especially in a form like podcasts, where an RSS feed allows a computer to download new episodes of shows without user intervention. It's possible to imagine a system where regular network TV shows are made available for download one or two days before they air—but in encrypted form. Then, "airing" the show would just entail distributing the decryption keys to viewers. This could leverage unused network capacity at night. Downloads might also happen using IP packets with a lower priority, so they don't get in the way of interactive network use.

IP addresses and home networks

A possible issue with IPTV could be the extra IP addresses required. There are basically two approaches to handling this issue: the one where the user is in full control, and the one where an IPTV service provider (usually the ISP) has some control. In the former case, streaming and downloading happens through the user's home network and no extra addresses are required. However, wireless home networks may not be able to provide bandwidth with enough consistency to make streaming work well, so pulling Ethernet cabling may be required.

When the IPTV provider provides a set-top box, it's often necessary to address packets toward that set-top box, so the box must be addressable in some way. This can eat up a lot of addresses, which is a problem in these IPv4-starved times. For really large ISPs, the private address ranges in IPv4 may not even be sufficient to provide a unique address to every customer. Issues in this area are why Comcast has been working on adopting IPv6 in the non-public part of its network for many years. When an IPTV provider provides a home gateway, this gateway is often outfitted with special quality-of-service mechanisms that make (wireless) streaming work better than run-of-the-mill home gateways that treat all packets the same.

Predicting the future

Converging to a single IP network that can carry the Web, other data services, telephony, and TV seems like a no-brainer. The phone companies have been working on this for years because that will allow them to buy cheap off-the-shelf routers and switches, rather than the specialty equipment they use now. So it seems highly likely that in the future, we'll be watching our TV shows over the Internet—or at least over an IP network of some sort. The extra bandwidth required is going to be significant, but so far, the Internet has been able to meet all challenges thrown at it in this area. Looking at the technologies, it would make sense to combine nightly pushed downloads for popular non-live content, multicast for popular live content, and regular streaming or peer-to-peer streaming for back catalog shows and obscure live content.

However, the channel flipping model of TV consumption has proven to be quite popular over the past half century, and many consumers may want to stick with it—for at least part of their TV viewing time. If nothing else, this provides an easy way to discover new shows. The networks are also unlikely to move away from this model voluntarily, because there is no way they'll be able to sell 16 minutes of commercials per hour using most of the other delivery methods. However, we may see some innovations. For instance, if you stumble upon a show in progress, wouldn't it be nice to be able to go back to the beginning? In the end, TV isn't going anywhere, and neither is the Internet, so they'll have to find a way to live together.

Correction: The original article incorrectly stated that cable providers get paid by TV networks. For broadcast networks, cable operators are required by the law's "must carry" provisions to carry all of the TV stations broadcast in a market. Ars regrets the error.

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Iljitsch van Beijnum
Iljitsch is a contributing writer at Ars Technica, where he contributes articles about network protocols as well as Apple topics. He is currently finishing his Ph.D work at the telematics department at Universidad Carlos III de Madrid (UC3M) in Spain. Emaililjitsch.vanbeijnum@arstechnica.com//Twitter@iljitsch

36 Reader Comments

In the cable TV world, this is very different: the cable TV providers get money from both TV networks and from consumers.

Ummm, no this is just wrong. ESPN does not pay for access, a few marginal or direct sales (home shopping channels) pay for access, a few pay for position, but the overwhelming direction of payments is from the cable co to the channels.

It's possible to imagine a system where regular network TV shows are made available for download one or two days before they air—but in encrypted form. Then, "airing" the show would just entail distributing the decryption keys to viewers. This could leverage unused network capacity at night. Downloads might also happen using IP packets with a lower priority, so they don't get in the way of interactive network use.

I don't think we'll ever see that model take off due to hackability reasons.

While interesting, the whole premise of the article is based on inside-the-box thinking. Live broadcasts aside for the moment, the concept that's being argued is how to fit the concept of the TV in the internet with things like time-slotted shows. That's stupid. Thanks to the internet, shows don't have to show up in any one "time slot" and can be best rolled out just like software updates, slowly and region by region over the course of a day (if really necessary).

Seriously, that's like 90% of this article. As for live streaming, it's certainly true that multicast could help here. Hell, some ISPs could be TRULY innovative for once, and dynamically figure out which video streams are hitting them the hardest at any given time and cache/relay them through the servers on their network. They don't even have to necessarily know what those packets are, just that they're being requested a lot and that each request doesn't have to go all the way out to the internet. Kind of how Dropbox works for files. But that would actually require TRUE innovation on the part of the ISPs, not just the kind that they want, which includes you continuing to subscribe to their overpriced video services.

In the cable TV world, this is very different: the cable TV providers get money from both TV networks and from consumers.

Ummm, no this is just wrong. ESPN does not pay for access, a few marginal or direct sales (home shopping channels) pay for access, a few pay for position, but the overwhelming direction of payments is from the cable co to the channels.

Working for a TV service provider I can say "++". They get your money and your balls, when it comes to sit down for discussions they call the shots. Some technologies that could be deployed already if the content providers didn't say 'no': network PVR (why does your STB need an HDD if we can stream stuff to you on demand?), record back (got home at 7:08 and missed the start of a show you forgot to record? no worries)

In the cable TV world, this is very different: the cable TV providers get money from both TV networks and from consumers.

Ummm, no this is just wrong. ESPN does not pay for access, a few marginal or direct sales (home shopping channels) pay for access, a few pay for position, but the overwhelming direction of payments is from the cable co to the channels.

Right, there's also money going in that direction, I should have mentioned that. The degree to which money flows in each direction also seems to differ between the US and Europe and other parts of the world.

The angle this article takes is that the problem is to try and emulate TV on the internet. But that's not how it should be done. TV works the way it does because it suits the technology used (ie radio broadcasts). It's not the way it is because that's what consumers wanted.

In the existing model TV networks play a big role. They own and control the distribution channels - radio spectrum licenses and private cable networks. The internet makes these obsolete and so it makes TV networks obsolete - the network is a middle man providing a service that's no longer need. Much like the newspaper industry. In they past to do a newspaper you needed a printing press, a lot of paper and trucks to deliver them. The people that had these controlled the media. Now you need an internet connection and a text editor - $0 entry cost. TV Networks are not needed on the internet.

TV is about TV shows, which is about video. Consumers want choice and control. The relationship should be between the content producer and the consumer. Jsut as everything else is on the web.

There's no technical reason why Matt Groening can't make an episode of the Simpsons available on thesimpsons.com each week downloadable with bittorrent. A video friendly version of RSS tells every subscribers TV about it when it's available. The TV could even grab it so it's ready to watch. A channel (web page) on the TV will tell you what's been released and what's been downloaded. You could subscribe to feeds that tell you about new shows you might be interested in.

I don't necessarily agree with some of the comments above that broadcast is redundant. In the UK market reality TV (X Factor) and sports (Football) will always have a demand for a live broadcast. Content providers also schedule TV shows to play on consumer interest. This isn't to say that there is no demand for on-demand TV. There certainly is and the popularity of iPlayer, 4OD, Demand Five, ITV Player, etc prove this. I'm assuming that other markets around the world don't vary much from this.

What we're seeing is that both broadcast and video on demand can actually live in harmony together. Projects which include TV tuners and IP connectivity such as YouView, scheduled for launch in early 2012 (yeah yeah, I'm not discounting its delays), as well as the 2011 TV models will all show this.

There's no technical reason why Matt Groening can't make an episode of the Simpsons available on thesimpsons.com each week downloadable with bittorrent. A video friendly version of RSS tells every subscribers TV about it when it's available. The TV could even grab it so it's ready to watch. A channel (web page) on the TV will tell you what's been released and what's been downloaded. You could subscribe to feeds that tell you about new shows you might be interested in.

Totally agree. However your cable / ADSL ISP is never going to want this to happen, they want to be in control so that they can charge you more money for a service that you can get for free over the TV and they want to be able to charge big companies delivery charges as well!

Surely though for the downloading of non live TV programmes this is crying out for some clever P2P solution to help take the strain off the content providers. In fact i believe Ars reported a trail in Scandinavia somewhere where a TV show was downloadable for free using bit torrent last year..

I don't necessarily agree with some of the comments above that broadcast is redundant. In the UK market reality TV (X Factor) and sports (Football) will always have a demand for a live broadcast. Content providers also schedule TV shows to play on consumer interest. This isn't to say that there is no demand for on-demand TV. There certainly is and the popularity of iPlayer, 4OD, Demand Five, ITV Player, etc prove this. I'm assuming that other markets around the world don't vary much from this.

What we're seeing is that both broadcast and video on demand can actually live in harmony together. Projects which include TV tuners and IP connectivity such as YouView, scheduled for launch in early 2012 (yeah yeah, I'm not discounting its delays), as well as the 2011 TV models will all show this.

I also work for an IPTV company. What we are seeing is, the customers want the best of both worlds, they are not excluding. Network PVR, Catchup-TV, YoutTube access, integration with streaming services; those are things that have an increasing demand. But do not forget that arriving at home, sitting on the couch, turning the TV on and just checking what they are broadcasting, without too much thinking, is fantastic, and people love it.

I haven't seen any serious study about the field that predicts the end of traditional-broadcast TV.

Was anybody interviewed for this? Any fact checking done? Or did some folks who know about the internet just deiced to sit down and pontificate?

I don't know where you guys 'followed the money' to but I can't image you being more wrong.

iljitsch wrote:

yasth wrote:

Quote:

In the cable TV world, this is very different: the cable TV providers get money from both TV networks and from consumers.

Ummm, no this is just wrong. ESPN does not pay for access, a few marginal or direct sales (home shopping channels) pay for access, a few pay for position, but the overwhelming direction of payments is from the cable co to the channels.

Right, there's also money going in that direction, I should have mentioned that. The degree to which money flows in each direction also seems to differ between the US and Europe and other parts of the world.

It's actually very similar to the systems in the EU if you swap in taxes and gov't broadcasters for cable networks and their channel operators. In both cases, a large number of people pay into a pooled system where the revenue is shared out to multiple content producing entities when then fill the networks with content. I know this is the case in the UK, Netherlands, Germany, and Belgium (as I have clients that are content networks in those countries.)

No system ANYWHERE is entirely ad supported. In either case, the fee collector is distributing in the area of billions of dollars. If you follow the money, it leads you to Comcast, not Akamai or Level3.

Quote:

Converging to a single IP network that can carry the Web, other data services, telephony, and TV seems like a no-brainer. The phone companies have been working on this for years because that will allow them to buy cheap off-the-shelf routers and switches, rather than the specialty equipment they use now. So it seems highly likely that in the future, we'll be watching our TV shows over the Internet—or at least over an IP network of some sort.

NEWSFLASH: YOU ALREADY AREIt's like this article was written by Borat for a Kazakh audience. Maybe they still have analogue cable, but I know guys who installed in Uzbekistan and Angola, so I think its safe to say most network providers have figured this out.

Do you think that HBO runs it's own VOD servers or something insane like that? Or that it comes off Level3 host machines? Or do you just think that the cable guys are too stupid to have figured out how to use files fo VOD?

Honestly Ars, this is talking out of one's ass. It's embarrassing.

Moving on tho this pie in the sky discussion about IPTV, 'TV over the Internet,' and the bit on set top boxes needing addresses...

You might not love Comcast's customer service, but writing an article predicated on the idea they their engineers are all fools just makes you look silly. Have you any idea the kind of technology that actually lives in a cable head end? Cable Lab's DOSSEC v3.0? IPTV is powering most content delivery world wide - it's technology that is bought and utilized by Network Providers (like Comcast and TWC) not by broadcasters or networks per se (tho many of these companies do have their own dark links over which they push multiplexed and/or packetized video as well as corporate data.)

If it was remotely possible, or profitable, to distribute multi-cast or any other kind of truly Broadcast experience the guys who run the engineering on these networks would have figured it out.

Quote:

However, multicast is very well suited to broadcast type network infrastructures, such as cable networks and satellite transmission. Launching multiple satellites that just send thousands of copies of the same packets to thousands of individual users would be a waste of perfectly good rockets.

It was a waste of a rocket to cover the entire continental united states. Those fools should have just put their shows up on Usenet!

The intellectual and journalistic laziness of this article is appalling and sad. IPTV is an extremely common technology leveraged on networks all over the world, but it has little to do w/ 'streaming content over the internet.' Browsing a few trade magazines would have gona a long way. You've missed the point entirely.

I don't necessarily agree with some of the comments above that broadcast is redundant. In the UK market reality TV (X Factor) and sports (Football) will always have a demand for a live broadcast. Content providers also schedule TV shows to play on consumer interest. This isn't to say that there is no demand for on-demand TV. There certainly is and the popularity of iPlayer, 4OD, Demand Five, ITV Player, etc prove this. I'm assuming that other markets around the world don't vary much from this.

What we're seeing is that both broadcast and video on demand can actually live in harmony together. Projects which include TV tuners and IP connectivity such as YouView, scheduled for launch in early 2012 (yeah yeah, I'm not discounting its delays), as well as the 2011 TV models will all show this.

Anymore, old school cable channels seem to be getting more and more like modern PayPerView channels (which themselves are less diverse than they used to be). Shows are rotated heavily and there are fewer shows being shown on a channel with a lot of churn in the episodes. You also have some bleed over effect between different channels where they are kind of overlapping each other's turf. That's kind of be to expected considering that channels have gotten ultra-specialized anymore. Although you also have channels kind of "branching out" and that just muddles things further.

A lot of stuff is repeats and duplicates and such and much of the 500 hundred channels on a modern cable lineup is fairly redundant with a lot of it being stuff you can just get off of Netflix or a bargain DVD.

Without the DMCA, I think buying and ripping would be a lot more commonplace and cable's position would be even more precarious than it is now as people would no longer see cable as a place to view back catalog stuff.

I suspect cable is in more danger than broadcast networks in this regard.

Cancelled cable here not too long ago and don't miss it. The old cable TV model is situated on total wastefulness. We had some 120 channel package and maybe watched a tenth of those channels. Most of the channels are worthless filler along with their content, just a total waste of money if you ask me. I think with the Internet, Cable TV providers are encountering something they never really had, competition. I hope the old model dies a horrible death because I am sick of paying for things I will never ever use or watch. That and the cable bills routinely go up several times a year.

Especially in a form like podcasts, where an RSS feed allows a computer to download new episodes of shows without user intervention. It's possible to imagine a system where regular network TV shows are made available for download one or two days before they air—but in encrypted form.

The Steam model would be good, especially since the pirates are already pretty much there. Any show you want is typically available via RSS feed about 30 minutes after it finishes airing. If you have a fast DSL\Uverse\FIOS connection you can be watching a pirated 720p version of a show before it airs on the west coast, and have it archived for later viewing. Streaming is good for "impulse" watching, but downloads are way better for shows that you plan to watch ahead of time. The networks really need to step up their game.

Was anybody interviewed for this? Any fact checking done? Or did some folks who know about the internet just deiced to sit down and pontificate?

No system ANYWHERE is entirely ad supported.

If that were true over-the-air television wouldn't exist. (Maybe some huckster is charging you for over-the-air television!)

I believe over-the-air television stations even pay to be put on cable channels, because it increases the audience for their advertisements, which is the source of the "cable TV providers get money from both TV networks and from consumers" quote.

When the IPTV provider provides a set-top box, it's often necessary to address packets toward that set-top box, so the box must be addressable in some way. This can eat up a lot of addresses, which is a problem in these IPv4-starved times.

Couldn't this be solved rather trivially by putting a wireless chip in the set-top box and letting it *be* the gateway? It wouldn't cover every power user, but there are a hell of a lot of people whose home network consists of a cheap 802.11 router plugged into a cable modem. Throw a small bank of ethernet ports on it and you'd have a convenient place to plug in other internet-aware entertainment boxes (roku, xbox, blu-ray, etc). Remote support would probably be easier too if you could verify the connection that first hop past the modem.

Who is satisfied with SDTV? I am amused at all the hot crowd who can't wait to use their hot new toy for low grade video on some kind of tiny screen. When I had no other choice, even 720 kbps was enough to get acceptable quality TV. But even with 7 mbps, video seems noticeably lower quality than OTA HDTV. There is no problem recording OTA HDTV and storing a large number of shows on terabyte hard drives. So the only real incentive is content that is not available on broadcast networks. Those who can't live without all the sports events from their favorite teams may have a problem. But I am happy with what I can get over the air at high quality plus some small amount of selected content from CNBC and similar sources that I can get in small chunks over the web at a low video quality that is more than adequate for that particular content.

How does their implementation of IPTV differ from what is described in the article?

It is described in the article. Typically they see how fast the line will support (it's just DSL for the last mile), then make sure that there is headroom for two HD channels above the speed they provision for the internet. For the faster connection though (where there isn't enough line speed for the sold internet capacity and the TV), watching TV can take away from available internet bandwith. The problem is when they try to do things like charge Netflix or throttle it. There is a huge conflict of interest allowing the telecoms to sell content. Wires, ISPs, and content providers should have to pick one role and be prohibited from being in the others. That's the only way to get fair access.

It's possible to imagine a system where regular network TV shows are made available for download one or two days before they air—but in encrypted form. Then, "airing" the show would just entail distributing the decryption keys to viewers. This could leverage unused network capacity at night. Downloads might also happen using IP packets with a lower priority, so they don't get in the way of interactive network use.

I don't think we'll ever see that model take off due to hackability reasons.

Not necessarily. If you do not give the key to the STB until the release date and use proper encryption there is no easy hackable way to get that stream encrypted.

The reason the current hacking works for BlueRay, DHCP ect... is that the decrytion key is on the box. If the key is not there until you don't care if everyone has the key there is no way to decrypt it in a reasonable amount of time.

How does their implementation of IPTV differ from what is described in the article?

It is described in the article. Typically they see how fast the line will support (it's just DSL for the last mile), then make sure that there is headroom for two HD channels above the speed they provision for the internet. For the faster connection though (where there isn't enough line speed for the sold internet capacity and the TV), watching TV can take away from available internet bandwith. The problem is when they try to do things like charge Netflix or throttle it. There is a huge conflict of interest allowing the telecoms to sell content. Wires, ISPs, and content providers should have to pick one role and be prohibited from being in the others. That's the only way to get fair access.

On the inside of that system - ADSL line comes into gateway router, each STB is connected via Ethernet, usually through a Gb switch. The gateway uses NAT for the internal addresses, so each gateway only uses one external IPv4 address.

Such an IPTV + Internet access service is a lot like what cable networks provide, but there is a crucial difference: with cable, the bandwidth of the analog cable signal is split into channels, which can be used for analog or digital TV broadcasts or for data. TV and data don't get in each other's way. With IPTV on the other hand, TV and Internet data are communication vessels: what is used by one is unavailable to the other

I don't know what you mean by "communication vessels". But anyway, with cable, the overall bandwidth is divided into channels, some reserved to data, mostly reserved for TV. The part not reserved for data is unavailable for data, right? You posit more contention between data and TV for what you're calling "IPTV" here, but really that just means either one is allowed to use as much as the entire pipe, with no reservations, which sounds *more* flexible.

If you're comparing something like DOCSIS 3 cable (lots of channels for video, and enough channels for video to hit 50mbps that I've seen and even faster in theory) to something like AT&T's U-verse IPTV (actually an ADSL2 connection for the last hop, so 24mbps of raw digital throughput, which is shared between data and TV), sure, DOCSIS 3 comes out way ahead, both in terms of # of video channels and amount of data throughput.

But that's because the coax cable had way more raw bandwidth -- there's more to go around, and even after dividing it up between TV and data they both come out ahead -- not because it allocates the available analog bandwidth more efficiently, as I read you saying. Pretty much the reverse is true.

"For broadcast networks, cable operators are required by the law's "must carry" provisions to carry all of the TV stations broadcast in a market. Ars regrets the error."

This is somewhat misleading too.

The must-carry rules only apply to broadcast networks that don't charge the cable companies license fees. The majority of major broadcast network local affiliates do now charge the cable companies licensing fess. That's the reason my local FOX affiliate was dumped by my cable company a few years ago and I had to watch the World Series on one of the spanish language channels.

FTA: "For instance, if you stumble upon a show in progress, wouldn't it be nice to be able to go back to the beginning?"

Yep, it sure is. With Time Warner, I can press SEL on the remote, then select "Start Over". (Also on the menu: 'Look Back' for shows broadcast the last 2-3 days near the current time slot, and 'High Definition' for conveniently skipping to the HD version of the channel.) I even get the ability to pause a replaying stream--at least for a limited amount of time. I've seen it switch back to live TV, but I haven't experimented to see if it's overflowing a local buffer, or if the server times out and cancels the stream.

And to think they wanted to try and make me rent a DVR, when they offer 80% of the utility for free.

Was anybody interviewed for this? Any fact checking done? Or did some folks who know about the internet just deiced to sit down and pontificate?

No system ANYWHERE is entirely ad supported.

If that were true over-the-air television wouldn't exist. (Maybe some huckster is charging you for over-the-air television!)

I believe over-the-air television stations even pay to be put on cable channels, because it increases the audience for their advertisements, which is the source of the "cable TV providers get money from both TV networks and from consumers" quote.

For less popular content, there's another delivery method that requires no or few streaming servers: peer-to-peer streaming. This was the technology used by the Joost service in 2007 and 2008. With peer-to-peer streaming, all the systems interested in a given stream get blocks of audio/video data from upstream peers, and then send those on to downstream peers. This approach has two downsides: the bandwidth of the stream has to be limited to fit within the upload capacity of most peers, and changing channels is a very slow process because a whole new set of peers must be contacted.

I think peer-to-peer streaming would work for very popular content. I've seen people watching sports on Stream Torrent. That just highlights one of the bigger issues with Internet TV: Internet applications don't mix easily with restrictive business practices based on geography.

I agree with many of the people posting a reply to this post: this article does nothing to explain what IPTV is.

I think Ars should seriously consider taking this post down because it is filled with inaccuracies and misconceptions (some of which have been fixed). However the most important thing is that IPTV is not delivered over the public Internet.

IPTV is the delivery of linear broadcast TV and VOD over a managed IP network typically by Telcos and other Service Providers (ISPs). IPTV is not Netflix, which is delivered over the public Internet--that's just called Internet video, or streaming or Internet TV. Take your pick.